Problem: Evaluate the following expression when $b = 5$ and $a = 6$. $9$ $b$ $ + 9$ $a$ $ + 7$
Explanation: Substitute $5$ for ${b}$ and $6$ for ${a}$ $ = 9{(5)} + 9{(6)} + 7 $ $ = 45 + 54 + 7 $ $ = 106$